The current invention is related to over-current fault detection, and in particular to a system and method for testing over-current fault detection in the field.
Excitation circuits are often used to control the application of power to a load. These circuits include switches which can be enabled or disabled to provide or cut off power to a load respectively. Excitation circuits, especially in critical systems such as those for jet engines, need to have over-current fault detection circuitry. In critical systems with multiple loads, it is also important to be able to isolate the specific fault from affecting the remaining system by switching off the excitation to only the individual faulted load.
An over-current fault is a fault in which there is an excess current flowing through a conductor. This excess current can be created by, among other things, a short-circuit fault in the load. Over-currents create excessive heat, which in turn creates a risk of fire or other damage to equipment. Therefore, it is necessary to detect over-current faults so that they can be handled and damage to the system can be prevented.
In the past, over-current fault handling has been tested by applying an external fault to the system. Because of this, the over-current fault handling circuitry could not be tested in the field. Testing could only occur during times when an external fault could be applied to the system. Therefore, if any problems arose in the over-current detection circuitry during normal system operation, those problems would not be detected and thus, any over-current faults would go unregulated. Further, test equipment used to apply an external fault increases overhead and production test costs.